android - 如何在没有互联网连接时阻止webview加载

Question

我有一个Android应用程序,它有一个webview.当没有互联网连接时,webview将显示页面不可用.我希望尽可能让它看起来像一个应用程序,所以我不想显示这个页面.我在网上找到了一些有用的信息,教你如何隐藏或加载其他内容来覆盖它,但我真正想要的是留在当前页面和一个小弹出对话框说没有连接.基本上,当用户点击webview中的任何内容时,首先检查连接.如果没有连接,请保持原状并弹出一个对话框.

谢谢您的帮助!!

编辑:

就像我说的,我已经知道如何从在线样本检查互联网连接.我的问题是我不知道如何停止加载下一页.需要说明的是,当用户尝试转到下一页时,请检查是否存在互联网连接.如果没有连接,页面将保持原样,不会进入下一页.我希望用户能够看到他们上次加载的页面,并在网页内容仍然存在时获得通知.谢谢!

Answer 1

我在我的项目中使用了以下内容:

DetectConnection.Java

import android.content.Context;
import android.net.ConnectivityManager;


public class DetectConnection {             
  public static boolean checkInternetConnection(Context context) {   

    ConnectivityManager con_manager = (ConnectivityManager) 
      context.getSystemService(Context.CONNECTIVITY_SERVICE);

    return (con_manager.getActiveNetworkInfo() != null
        && con_manager.getActiveNetworkInfo().isAvailable()
        && con_manager.getActiveNetworkInfo().isConnected());
  }
}

主要代码:

if (!DetectConnection.checkInternetConnection(this)) {
  Toast.makeText(getApplicationContext(), "No Internet!", Toast.LENGTH_SHORT).show();
} else {      
  wv = (WebView) findViewById(R.id.donate_webView1);
  c = new CustomWebViewClient();
  wv.setWebViewClient(c);
  wv.clearCache(true);
  wv.clearHistory();
  wv.getSettings().setJavaScriptEnabled(true);
  wv.getSettings().setJavaScriptCanOpenWindowsAutomatically(true);
  wv.getSettings().setBuiltInZoomControls(true);
  wv.loadUrl("http://www.google.com");
}


// Function to load all URLs in same webview
private class CustomWebViewClient extends WebViewClient {
  public boolean shouldOverrideUrlLoading(WebView view, String url) {
    if (!DetectConnection.checkInternetConnection(this)) {
      Toast.makeText(getApplicationContext(), "No Internet!", Toast.LENGTH_SHORT).show();
    } else {
      view.loadUrl(url);
    }     
    return true;
  }
}

更新清单:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

Answer 2

你可以用我的CustomWebViewClient-

• 在加载网页时显示加载对话框
• 在页面加载失败的情况下显示错误消息
• 在没有Internet的情况下,它为用户提供了设置和启用移动数据的选项.
• 在其他类型的错误的情况下,它允许用户重新加载网页.

您需要做的就是将它附加到您的webView

webView.setWebViewClient(new CustomWebViewClient());

CustomWebViewClient类

    /**
     * WebViewClient subclass loads all hyperlinks in the existing WebView
     */
    public class CustomWebViewClient extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            // When user clicks a hyperlink, load in the existing WebView
            view.loadUrl(url);
            return true;
        }

        Dialog loadingDialog = new Dialog(WebViewActivity.this);

        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            super.onPageStarted(view, url, favicon);
            webViewPreviousState = PAGE_STARTED;

            if (loadingDialog == null || !loadingDialog.isShowing())
                loadingDialog = ProgressDialog.show(WebViewActivity.this, "",
                        "Loading Please Wait", true, true,
                        new DialogInterface.OnCancelListener() {

                            @Override
                            public void onCancel(DialogInterface dialog) {
                                // do something
                            }
                        });

            loadingDialog.setCancelable(false);
        }


        @RequiresApi(api = Build.VERSION_CODES.M)
        @Override
        public void onReceivedError(WebView view, WebResourceRequest request,
                                    WebResourceError error) {


            if (isConnected()) {
                final Snackbar snackBar = Snackbar.make(rootView, "onReceivedError : " + error.getDescription(), Snackbar.LENGTH_INDEFINITE);
                snackBar.setAction("Reload", new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        webView.loadUrl("javascript:window.location.reload( true )");
                    }
                });
                snackBar.show();
            } else {
                final Snackbar snackBar = Snackbar.make(rootView, "No Internet Connection ", Snackbar.LENGTH_INDEFINITE);
                snackBar.setAction("Enable Data", new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        startActivityForResult(new Intent(Settings.ACTION_WIRELESS_SETTINGS), 0);
                        webView.loadUrl("javascript:window.location.reload( true )");
                        snackBar.dismiss();
                    }
                });
                snackBar.show();
            }

            super.onReceivedError(view, request, error);

        }

        @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
        @Override
        public void onReceivedHttpError(WebView view,
                                        WebResourceRequest request, WebResourceResponse errorResponse) {

            if (isConnected()) {
                final Snackbar snackBar = Snackbar.make(rootView, "HttpError : " + errorResponse.getReasonPhrase(), Snackbar.LENGTH_INDEFINITE);

                snackBar.setAction("Reload", new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        webView.loadUrl("javascript:window.location.reload( true )");
                    }
                });
                snackBar.show();
            } else {
                final Snackbar snackBar = Snackbar.make(rootView, "No Internet Connection ", Snackbar.LENGTH_INDEFINITE);
                snackBar.setAction("Enable Data", new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        startActivityForResult(new Intent(Settings.ACTION_WIRELESS_SETTINGS), 0);
                        webView.loadUrl("javascript:window.location.reload( true )");
                        snackBar.dismiss();
                    }
                });
                snackBar.show();
            }
            super.onReceivedHttpError(view, request, errorResponse);
        }

        @Override
        public void onPageFinished(WebView view, String url) {

            if (webViewPreviousState == PAGE_STARTED) {

                if (null != loadingDialog) {
                    loadingDialog.dismiss();
                    loadingDialog = null;
                }
            }
        }
    }

检查连接方法

    /**
     * Check if there is any connectivity
     *
     * @return is Device Connected
     */
    public boolean isConnected() {

        ConnectivityManager cm = (ConnectivityManager)
                this.getSystemService(Context.CONNECTIVITY_SERVICE);

        if (null != cm) {
            NetworkInfo info = cm.getActiveNetworkInfo();
            return (info != null && info.isConnected());
        }

        return false;

    }